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Diffstat (limited to 'Documentation/xtensa/atomctl.txt')
-rw-r--r-- | Documentation/xtensa/atomctl.txt | 44 |
1 files changed, 0 insertions, 44 deletions
diff --git a/Documentation/xtensa/atomctl.txt b/Documentation/xtensa/atomctl.txt deleted file mode 100644 index 1da783ac200c..000000000000 --- a/Documentation/xtensa/atomctl.txt +++ /dev/null @@ -1,44 +0,0 @@ -We Have Atomic Operation Control (ATOMCTL) Register. -This register determines the effect of using a S32C1I instruction -with various combinations of: - - 1. With and without an Coherent Cache Controller which - can do Atomic Transactions to the memory internally. - - 2. With and without An Intelligent Memory Controller which - can do Atomic Transactions itself. - -The Core comes up with a default value of for the three types of cache ops: - - 0x28: (WB: Internal, WT: Internal, BY:Exception) - -On the FPGA Cards we typically simulate an Intelligent Memory controller -which can implement RCW transactions. For FPGA cards with an External -Memory controller we let it to the atomic operations internally while -doing a Cached (WB) transaction and use the Memory RCW for un-cached -operations. - -For systems without an coherent cache controller, non-MX, we always -use the memory controllers RCW, thought non-MX controlers likely -support the Internal Operation. - -CUSTOMER-WARNING: - Virtually all customers buy their memory controllers from vendors that - don't support atomic RCW memory transactions and will likely want to - configure this register to not use RCW. - -Developers might find using RCW in Bypass mode convenient when testing -with the cache being bypassed; for example studying cache alias problems. - -See Section 4.3.12.4 of ISA; Bits: - - WB WT BY - 5 4 | 3 2 | 1 0 - 2 Bit - Field - Values WB - Write Back WT - Write Thru BY - Bypass ---------- --------------- ----------------- ---------------- - 0 Exception Exception Exception - 1 RCW Transaction RCW Transaction RCW Transaction - 2 Internal Operation Internal Operation Reserved - 3 Reserved Reserved Reserved |